Genes and Immunity (2014) 15, 190–194 & 2014 Macmillan Publishers Limited All rights reserved 1466-4879/14 www.nature.com/gene SHORT COMMUNICATION SPAG7 is a candidate gene for the periodic fever, aphthous stomatitis, pharyngitis and adenopathy (PFAPA) syndrome S Bens1, T Zichner2, AM Stu¨tz2, A Caliebe1, R Wagener1, K Hoff1,3, JO Korbel2, P von Bismarck4 and R Siebert1 Periodic fever, aphthous stomatitis, pharyngitis and adenopathy (PFAPA) syndrome is an auto-inflammatory disease for which a genetic basis has been postulated. Nevertheless, in contrast to the other periodic fever syndromes, no candidate genes have yet been identified. By cloning, following long insert size paired-end sequencing, of a de novo chromosomal translocation t(10;17)(q11.2;p13) in a patient with typical PFAPA syndrome lacking mutations in genes associated with other periodic fever syndromes we identified SPAG7 as a candidate gene for PFAPA. SPAG7 protein is expressed in tissues affected by PFAPA and has been functionally linked to antiviral and inflammatory responses. Haploinsufficiency of SPAG7 due to a microdeletion at the translocation breakpoint leading to loss of exons 2–7 from one allele was associated with PFAPA in the index. Sequence analyses of SPAG7 in additional patients with PFAPA point to genetic heterogeneity or alternative mechanisms of SPAG7 deregulation, such as somatic or epigenetic changes. Genes and Immunity (2014) 15, 190–194; doi:10.1038/gene.2013.73; published online 23 January 2014 Keywords: SPAG7; PFAPA; periodic fever; chromosomal translocation INTRODUCTION of 84 (45%) patients there was a family history of recurrent fever.9 Periodic fever, aphthous stomatitis, pharyngitis and adenopathy The high frequency of a recurrent fever other than PFAPA in the (PFAPA) syndrome is an auto-inflammatory disorder first described families of the patients is in line with the observation that patients by Marshall et al. in 1987.1 It is characterised by fever episodes with PFAPA syndrome show an increased probability to be carriers lasting 3–6 days with a recurrence every 3–8 weeks, exudative of heterozygous mutations in one of the genes associated with tonsillitis, cervical adenopathy and malaise in all and aphthae in the other familial periodic fever syndromes.10 In particular, the majority of patients.2–5 Headache, abdominal pain and heterozygous mutations in the MEFV gene associated with FMF arthralgia are also recurrently observed. are frequent in PFAPA patients. Such MEFV mutations might Owing to the recurrent fever episodes PFAPA has been assigned modify the clinical course of the disease.11 to the clinical spectrum of (periodic) fever syndromes. These also Overall, molecular data, along with the absence of a clear include familial Mediterranean fever (FMF MIM #134610/#249100, monogenetic trait despite significant familial clustering, might associated gene MEFV*608107), TNF receptor-associated periodic point to a polygenetic or multifactorial origin of PFAPA rather than fever syndrome (TRAPS #142680, gene TNFRSF1A*191190), hyper- a monogenetic predisposition. Part of this predisposition might be immunoglobulinaemia D (HIDS #260920, gene MVK*251170), conferred by sequence variants in inflammasome-associated cryopyrin-associated periodic syndrome (CAPS) including familial genes like NLRP3. These have been described in B20% of cold auto-inflammatory syndrome (FCAS1 #120100, gene patients with PFAPA.10 Such variants might increase the NLRP3*606416, and FCAS2 #611762, NLRP12*609648), Muckle– probability of dysregulated interleukin 1b production by Wells syndrome (MWS #191900, gene NLRP3*606416) and monocytes during febrile episodes typical for PFAPA neonatal onset multisystem inflammatory disease (NOMID/CINCA syndrome.10 Overall, the hitherto published functional studies #607115, gene NLRP3*606416).6,7 Remarkably, all of these fever point to a pathophysiologic model of PFAPA syndrome in which syndromes are monogenetically inherited disorders for which the microbial triggers activate a cascade that begins with the innate responsible genes have been identified. Interestingly, this does immune system and ultimately recruits activated T cells to the not hold true yet for PFAPA syndrome. periphery.12 Thus, PFAPA syndrome could be due to an abnormal Despite the current lack of a candidate gene for PFAPA adaptive immune response to viral or other infectious agents, syndrome, various studies point to the fact that this auto- likely at the level of lymphoid organs, able to induce a rapid inflammatory disease is not a sporadic disorder but based on a activation of cells of innate immunity.8,13 This infectious-origin genetic predisposition.8 Major epidemiologic evidence for this hypothesis at the level of lymphoid organs would be well in line assumption comes from the observations by Cochard et al.9 These with the histology of tonsils of patients with PFAPA syndrome, authors showed that a significant percentage of PFAPA patients which shows non-specific chronic inflammation, characterised by presents a positive family history of recurrent fever in general and lymphoid and follicular immunoblastic hyperplasia, focal of PFAPA in particular.9 Indeed, in this study, 10 of 84 (12%) histiocytic clusters, hyalinising fibrosis, crypt abscesses and patients had a relative affected with PFAPA syndrome. Even in 38 keratinising debris.14 1Institute of Human Genetics, Christian-Albrechts-University Kiel & University Hospital Schleswig-Holstein, Kiel, Germany; 2European Molecular Biology Laboratory (EMBL), Genome Biology Research Unit, Heidelberg, Germany; 3Department of Congenital Heart Disease and Pediatric Cardiology, Christian-Albrechts-University Kiel & University Hospital Schleswig-Holstein, Kiel, Germany and 4Department of Pediatrics, Christian-Albrechts-University Kiel & University Hospital Schleswig-Holstein, Kiel, Germany. Correspondence: Dr S Bens, Institute of Human Genetics, Christian-Albrechts-University Kiel & University Hospital Schleswig-Holstein, Campus Kiel, Arnold-Heller Str. 3 (Haus 10), D-24105 Kiel, Germany. E-mail: [email protected] Received 9 November 2013; revised 15 December 2013; accepted 16 December 2013; published online 23 January 2014 SPAG7 in PFAPA syndrome S Bens et al 191 It has recently been shown that cloning of breakpoints of de chromosome analyses on the peripheral blood of the parents novo balanced chromosomal translocations in patients with revealed normal karyotypes in both mother and father. Thus, the phenotypic abnormalities of unknown origin can lead to the t(10;17) was a de novo event in the patient. Given that both identification of disease-causing genes.15,16 We have adapted this parents are generally healthy and particularly have neither signs of strategy here to PFAPA and characterised the breakpoints of a de PFAPA syndrome nor any other reported autoimmune or auto- novo chromosomal translocation in a patient with PFAPA inflammatory disease, the de novo appearance of both PFAPA syndrome without family history of recurrent fevers and lacking syndrome and the translocation might point to a causal relation- mutations in known genes associated with recurrent fever ship. Indeed, it has been shown that carriers of a de novo balanced syndromes, with the use of massively parallel DNA sequencing. chromosomal rearrangement have a two- to threefold increased By this approach we have identified herein SPAG7 as a novel risk for congenital anomalies.15,17 Consequently, cloning the candidate gene for PFAPA syndrome. The finding of de novo breakpoints of such de novo balanced chromosomal haploinsufficiency of the SPAG7 gene in the patient, the rearrangements in patients with phenotypic abnormalities of expression of the SPAG7 protein in tonsils and lymph nodes, as unknown origin has been successfully applied to identify disease- well as the evidence for its involvement in antiviral and causing genes.15,16 inflammatory responses are in full agreement with the above- In order to exclude a submicroscopic chromosomal imbalance outlined models of PFAPA pathogenesis. related or unrelated to the chromosomal translocation we performed array-comparative genomic hybridisation with a functional resolution of 0.1 Mb. Besides well-known copy number RESULTS AND DISCUSSION variations, no imbalances were detected at the resolution applied. Aiming at identifying potential genetic causes of PFAPA syndrome In particular, we did not detect any imbalances around the we investigated whether a chromosomal aberration had been cytogenetically assigned breakpoints. Moreover, pathogenic diagnosed in any of the patients presented at our institution with sequence variants in genes associated with periodic fever this auto-inflammatory disorder. Using this approach, we identi- syndromes or auto-inflammatory diseases, that is, MEFV, NLRP3, fied a girl with typical clinical features of PFAPA syndrome in NLRP12, ELA2, TNFRSF1A, MVK and CARD15, as a cause or modifier whom prior to this diagnosis a chromosome analysis on peripheral of the phenotype were excluded. blood lymphocytes had been performed due to growth retarda- Given the cytogenetically and molecular cytogenetically tion, facial dysmorphisms and dysplastic brachymesophalangy V balanced-appearing change and the lack of mutations in genes (for a detailed clinical description see the clinical synopsis in associated with periodic fever syndromes, we wondered whether Materials and methods). G-banded karyotyping at 400 bphs the translocation might lead to disruption or otherwise deregula- revealed a cytogenetically balanced